The present invention relates generally to gas turbine engine fuel nozzles, and more particularly to a fitting for connecting a nozzle to a supply line.
Gas turbine engines generally have a compressor section for compressing flowpath air traveling through the engine, a combustor downstream from the compressor section for heating the compressed flowpath air, and a turbine section downstream from the combustor for removing energy from the heated flowpath air to drive the compressor section. The combustor includes fuel nozzles for delivering fuel to the combustor. The fuel nozzles have a fuel inlet that connects to a fuel supply line and an outlet that delivers the fuel to the combustor. Conventionally, the fuel nozzle inlet is formed as a protrusion having a rounded sealing surface and external threads. The fuel supply line has an annular conical seat that mates with the rounded sealing surface. An internally threaded nut is used to connect the fuel supply line to the inlet and hold the annular seat in sealing engagement with the rounded sealing surface.
In some applications, a frame surrounds the combustor immediately outside the fuel nozzles, and the fuel nozzles are cooled with cooling air. A separate cooling air supply line is provided for delivering the cooling air to passages extending through the nozzle. A protruding inlet similar to that used for the fuel supply line cannot be used to connect the cooling air supply line to the fuel nozzle because such an inlet configuration does not provide sufficient radial clearance between the fuel nozzles and the surrounding frame during assembly. Thus, there is a need for a fuel nozzle having a low profile cooling air inlet.